Reduction of satellite flywheel microvibration using rubber shock absorbers

Microvibration of flywheels strongly affects the imaging quality of space cameras. A passive vibration method is used in this study to reduce the effect of microvibration. A rubber shock absorber was designed and installed on a satellite. The angular displacement of the second mirror was measured via a fiber optic gyroscopic method. The measured data were imported into MATLAB and analyzed by different methods. The data was plotted as a root-mean-square graph of angular displacement at different speeds along the x-axis, a waterfall plot of the attenuation of force in the x direction, the vibration spectrum between the frequency and displacement amplitude, and the time domain response of the inverse Fourier transform of the spectrum. The results show that the microvibration of the flywheel causes significant vibration of the imaging system, and that adding a rubber shock absorber can reduce the vibration. The proposed method is a new attempt to analyze microvibration, and can be applied to the engineering design of flywheels

Reduction of satellite flywheel microvibration using rubber shock absorbers

Microvibration of flywheels strongly affects the imaging quality of space cameras. A passive vibration method is used in this study to reduce the effect of microvibration. A rubber shock absorber was designed and installed on a satellite. The angular displacement of the second mirror was measured via a fiber optic gyroscopic method. The measured data were imported into MATLAB and analyzed by different methods. The data was plotted as a root-mean-square graph of angular displacement at different speeds along the x-axis, a waterfall plot of the attenuation of force in the x direction, the vibration spectrum between the frequency and displacement amplitude, and the time domain response of the inverse Fourier transform of the spectrum. The results show that the microvibration of the flywheel causes significant vibration of the imaging system, and that adding a rubber shock absorber can reduce the vibration. The proposed method is a new attempt to analyze microvibration, and can be applied to the engineering design of flywheels

One‐year status of hepatic venous pressure gradient measurement from 85 hospitals in China

Abstract Aims Surveys and research on the applications of the hepatic venous pressure gradient (HVPG) are important for understanding the current status and future development of this technology in China. This article aimed to investigate the status of hepatic venous pressure gradient measurement in China in 2022. Methods We investigated the overall status of HVPG technology in China—including hospital distribution, hospital level, annual number of cases, catheters used, average cost, indications, and current challenges by using online questionnaire. By counting the number and percentages of cases of these results, we hope to clarify the current status of HVPG measurements in China. Results According to the survey, 85 hospitals in China used HVPG technology in 2022 distributed across 29 provinces. A total of 4989 HVPG measurements were performed in all of the surveyed hospitals in 2022, of which 2813 cases (56.4%) were measured alone. The average cost of HVPG measurement was 5646.8 ± 2327.9 CNY. Of the clinical teams who performed the measurements (sometimes multiple per hospital), 94.3% (82/87) used the balloon method, and the majority of the teams (72.4%, 63/87) used embolectomy catheters. Conclusions This survey clarified the clinical application status of HVPG in China and confirmed that some medical institutions in China have established a foundation for this technology. It is still necessary to continue promoting and popularizing this technology in the future